FREQUENCY_INDICATOR_

Published:2009/7/1 5:29:00 Author:May | From:SeekIC

|Circuit furnishes green indication at resonance and red for either side of resonance. Uses Monsanto MV5491 dual redlgreen LED, with 220 ohms in upper lead to +5 V supply and 100 ohms in lower +5 V lead because red and green LEDs in parallel back-to-back have different voltage requirements. Useful for SSTV, RTTY, or subaudio-tone indication for control purposes on FM. Circuit requires two driver ICs and one section of hex inverter IC, with any suitable active filter used to form level detector for signals at desired frequency.-K.Powell, Novel Indicator Circuit, Ham Radio, April 1977, p 60-63.



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